Snowy owls have been spotted far south of their usual range in the boreal forest this winter. The birds have been heading south in large numbers, surprising and delighting many bird watchers.

Snowy owls nest in the arctic regions of Canada, Alaska and Eurasia, but are known to head south when their population spikes or their main food source, lemmings, becomes scarce.

Every year a few snowy owls are spotted in a handful of U.S. states, but this year some researchers believe the sightings may reach record numbers. Scientists at The Cornell Lab of Ornithology say irruptions -- when birds migrate beyond their usual range -- for snowy owls occur about every four years. During irruption years the birds have been spotted as far south as Florida, Texas and California.

This winter's irruption has been so dramatic, it's prompted the American Birding Association to state that the invasion is "getting crazier by the minute."

Sightings of a snowy owl in Florida's Little Talbot Island Park made headlines this week in Jacksonville:

WOW!! Snowy owl invasion of US extends to #Florida; only third ever sighting in Florida - http://t.co/CE1pCyNoCg - http://t.co/pgvumldH9wNews4Jax

#birds - Snowy #Owl was a life #bird for 2013. Very rare for Florida. #birding #nature http://t.co/uJCyeM8NVNFlying True North